1. Field of the Invention
The present invention is generally related to gaskets of the type used to establish a gas-tight seal between two members to be clamped together and more particularly to cylinder head gaskets.
2. Related Art
In establishing a gas-tight seal between two members to be clamped together, such as a cylinder head and an engine block, it is common to use a cylinder head gasket having one or more layers. Generally, at least one of the layer(s), sometimes referred to as a functional layer, has a compression bead which deforms elastically when sandwiched between the cylinder head and engine block to establish the gas-tight seal. The gasket may also include one or more distance layers, which may be configured to backload stoppers and limit the compression of the compression bead, thereby improving fatigue resistance. Unfortunately, while fastening the cylinder head to the engine block, the compression bead can be over-compressed and substantially flattened. If the compression bead is over-compressed, in addition to losing its ability to maintain a gas-tight seal, fatigue cracks can form in the area of the compression bead during the initial clamping or while in use. Fatigue cracks can also be formed by movement of the cylinder head lifting upwardly during combustion in the cylinder then compressing back down on the gasket. If formed, fatigue cracks ultimately reduce the ability of the static gasket to maintain a gas-tight seal, thereby diminishing the life and performance of the engine.
Some gasket manufacturers have begun producing multi-layer gaskets including compression limiters for preventing, or at least reducing, flattening of the compression bead between the cylinder head and engine block. However, these compression limiters are often costly and laborious to produce or may not sufficiently protect the compression bead from flattening.